1. Field of the Disclosure
The present disclosure generally relates to a control method and control system for an audio device, and, more particularly, to a control method and control system for a Universal Serial Bus (USB) audio adapter.
2. Description of Related Art
The function of a USB audio adapter is to convert audio signals between the USB interface and the analog audio interface. There are two common USB audio adapters: one contains two audio jacks and the other contains only one audio jack. For the application of the USB audio adapter with two audio jacks, one of the audio jacks is dedicated to audio output devices such as headphones, and the other is dedicated to audio input devices such as microphones. For the application of the USB audio adapter with only one audio jack, the audio jack supports both audio output and audio input, and so the audio jack can be connected to headphone devices, microphone devices, or headset devices. Headset devices refer generally to devices having both the headphone function and the microphone function.
After the USB audio adapter is connected to a host (e.g., a device with a USB interface such as a computer, a portable electronic product, etc.), the host enumerates the USB audio adapter as an appropriate device according to the declaration type of the USB audio adapter. More specifically, because the USB audio adapter provides at least the function of connecting to the headphone and the microphone, the host enumerates the USB audio adapter as a headset device after the USB audio adapter is connected to the host. Once enumerated, regardless of the type of the device (a pure headphone device, a pure audio output device, a pure microphone device, a pure audio input device, a headset device, a device including audio input/output, or even the audio jack is not connected to any device) that is connected to the audio jack of the USB audio adapter, the host directs the audio data to this USB audio adapter, instead of using the built-in audio devices (such as built-in speaker, microphone, etc.) for audio playback or picking up the sound. Such a design, however, may cause inconveniences to users. For example, when the device connected to the USB audio adapter is a pure headphone device, the user expects that the host still uses the built-in microphone to pick up the sound; unfortunately, the practical situation is that the host attempts to use the USB audio adapter for both picking up the sound and audio playback, thereby failing to pick up the sound.